London. Christmas is coming. Prematurely mature Adam Killjoy, new head of cyber security at AFS Financial Services, has problems. He hates Xmas. His humourless girlfriend of one year is taking charge of his life and lumbering towards marriage without consent. His co-worker, Jessica Chill, is convinced she will make him a far more suitable Mrs (i.e. Boss). She is trying to dump her boyfriend Bare Girls, an insanely jealous bodybuilder and psychopathic village idiot. Adam's career is about to implode. He has nerve-shredding nightmares every time he momentarily manages to drift off to sleep. An email pops into his inbox. It's a special offer from Whoo-Hoo-Dunnit-Hollidaze, a company specialising in weeks away for those fascinated by whodunnits. Adam presumes it to be a scam. Another email appears, from the HR software, telling him he has to take eleven days annual holiday or loose [sic] it. It's the camel's back's straw. He takes leave of his senses and heads off for a week of inhibition-free Whoo-Hoo-Dunnit.
First he has to shepherd Cheri Cherioki across to the same venue, a ditzy eighteen-going-on-twelve-year old with a screaming violin who claims to be a singing celebrity. They are driven from the airport to the villa by Philippe, where they are met by his cousin Enri. On the second day there they are joined to Adam's horror by Jessica Chill. That evening Adam has a nightmare in which Bare Girls is trying to climb through his second-floor bedroom window to murder him. It's no nightmare: Bare has turned up. He and Adam find Jessica dead in her room. On the fourth evening Adam has a nightmare where a dead Jessica is trying to climb through the same bedroom window. Armed only with a second-hand copy of "The Dos and Donuts of Whodunnits" a desperate Adam interrogates all the other guests, intent on identifying who is narrating the whodunnit and who will turn out to have dunnit: gorgeous but mysterious Nanette the Newsreader from Nancy; The Bishop of Bordeaux, a regretfully celibate sage; The Mayor of Montpellier, ex-politician and criminal; The Chef from Charleroi, a cook with a cleaver; The Journalist from Grenoble, a man who saw too much; Mademoiselle The Madman from Marseilles; The Psychologist from Sicily; The Artist from Algiers, a painter who suffered too many grains of sand; and François The Fortune Teller from Fontainebleau with good news. With each interrogation he feels he is getting further from the secret of Whoo-Hoo-Dunnit-Hollidaze, but each suspect drags out a little more of the mystery of why Adam hates Christmas.